Hello Prajjwal!

To get admission in B.Sc. in St. Xavier's College, Mumbai, you will be selected on the basis of your Class 12th aggregate percentage. No entrance exam will be conducted.
Apart from  Bachelor in Management Studies (BMS) and Bachelor in Mass Media courses, entrance exams are not conducted for UG and PG - level courses in this college. Admission to these courses is based on 60% weightage for Entrance Test and 40% weightage for Class 12th aggregate marks.

You'll simply have to fill up its online application available on the official website with your correct details and stay updated for the release of selected candidates by the authority.

Don't hesitate to ask if you have any more queries.
I hope this answer will help you.
Best wishes!